According to a new study, heart attack patients who are given the blood thinner Plavix together with heartburn drug like Prilosec or Nexium nearly double their risk of another heart attack.

Made by Sanofi-Aventis SA and Bristol-Myers Squibb Co, Plavix, also known as clopidogrel and aspirin are used in heart attack patients to thin their blood as the drug makes blood platelets less sticky, helping to prevent clots from forming.

Often doctors prescribe a proton pump inhibitor, or PPI, such as AstraZeneca Plc's heartburn drug Prilosec to cut the risk of gastrointestinal bleeding from blood thinners. Dr. P. Michael Ho, a cardiologist at the Denver VA Medical Center and lead researcher of the study said, "A lot of patients are on Plavix and also a lot of patients are being prescribed PPI medication just prophylactically to prevent a stomach bleed."

The study published in the Journal of the American Medical Association tracked 8,205 patients discharged from 127 Veterans Affairs hospitals after suffering a heart attack or unstable angina and out of these 63.9 % were prescribed a proton pump inhibitor.

The researchers noted that 29.8 % of the patients who were given a PPI and Plavix died or were re-hospitalized, compared with 20.8 % of the patients who were given only Plavix. This showed an increase in the risk of dying or being re-hospitalized of 25 % in the patients who received a combination of Plavix and PPI compared to the ones on Plavix alone.

The risk of hospitalization was seen to be greater when both drugs were given but the risk of dying was seen to be the same even if only Plavix was given. Ho said this drug combination may be responsible for thousands of repeat heart attacks.

"Our study highlights a potential interaction between clopidogrel and PPI medication. And it suggests that maybe PPI medication should not just be prescribed routinely or prophylactically in patients who are on aspirin and clopidogrel," Ho said.

Some doctors disagree and Dr. Kirk Garratt of Lenox Hill Hospital in New York said, "We have to be really careful with this study. If we stop prescribing PPIs for these patients, we will see more bleeding complications. A big bleed for a patient with significant coronary artery disease could easily prove fatal."

Ho said PPIs are often prescribed to patients who do not need them. "There are quite a number of patients who are prescribed PPIs as a matter of fact without a bleeding indication," he said.

He added that the use of PPIs should be discussed by patients who are already using Plavix. This should be an individualized decision between the patient and the physician about whether patients should be on a PPI or whether there are alternative medications for reflux or stomach problems," he said.

Dr. Byron Lee, an associate professor of cardiology at the University of California, San Francisco said, "This study is very worrisome because so many of our patients are on both Plavix and a proton pump inhibitor. To lower the risk of recurrent heart attacks, we should probably think about switching some of these patients from proton pump inhibitors to H2 blockers [such as Zantac or Tagamet], at least temporarily."

Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles said, "The FDA [Food and Drug Administration] has recently communicated that it is conducting a safety review regarding potential interactions of these two commonly prescribed medications."

Ho summed it up by saying that the study doesn't change the reasons for prescribing Plavix, "But both clinicians and patients should look at why the PPI is being prescribed. It shouldn't be prescribed prophylactically just to prevent a GI bleed, because there might be an interaction between the PPI and Plavix," he said.